Process for production of fertilizers



Patented Apr. 13, 1937 UNITED STATES 2,077,171 raoo'sss ron rnonuo'rron or FER-' TILIZERS Edward W. Harvey, New Brunswick, N. J., and Russell M. Jones, Shefiield, Ala, assignors to The Barrett Company, New York, N. Y., a corporation of New Jersey No Drawing. Application February 26, 1934, Serial No. 713,046. In Canada December 18, 193

3 Claims.

This application is a continuation in part of our cope'nding United States application, Serial No. 485,298, filed September 29, 1930.

This invention relates to the production of fer 5 tilizers from a superphosphate (superphosphate or triple superphosphate) or mixtures containing a superphosphate, by the treatment of such material with ammonium nitrate and ammonia.

superphosphate, which is the product obtained by decomposing phosphate rock with sulfuric acid, is commonly employed in the preparation of fertilizer mixtures as a source of phosphorus.

It contains principally monocalciumphosphate and calcium sulfate. Triple superphosphate is 10 prepared by decomposing phosphate. rock with phosphoric acid, and principally consists of monocalcium phosphate with some free phosphoric acid. It is also desirable in preparing mixed fertilizers from a superphosphate to inelude a material containing nitrogen in a form in which it is available as a food for plants. Am-

monia is a convenient and relatively inexpensive source of such nitrogen and is moreover a desirable addition to superphosphate because it neu- 2 tralizes free acid therein and affords heat by chemical reaction which drives off a part of the free moisture. Accordingly, numerous procedures for the treatment of a superphosphate with ammonia have been proposed.

The addition of ammonia causes monocalclum acid phosphate of the superphosphate which is soluble in water to be transformed into a calcium phosphate which is relatively insoluble in water a but soluble in citrate solution and is thus known as citrate-soluble. If a large amount of ammonia is added to superphosphate or triple superphosphate, an excessive amount of water soluble and citrate soluble phosphate, which are both considered available as plant food, is reverted to a citrate insoluble or unavailable form. Consequently, the amount of ammonia which heretofore could be added to superphosphate was limited and the advantages of this source of nitrogen in fertilizer mixtures containing superphosphate could not be fully secured.

It is an object of the present invention to reduce the formation of unavailable phosphorus in the treatment of superphosphate or mixtures containing the same with ammonia and to make possible the use of relatively large quantities of ammonia with such materials without excessively reducing the fertilizing value 'of the phosphate contained therein. It is a further object of this invention to provide a process for the preparation of mixed fertilizers including superphosphate, which fertilizers contain a relatively large proportion of nitrogen both as ammoniacal nitrogen and as nitrate nitrogen and in which the P205 content of the superphosphate remains in large part in the form in which it is available as plant food, particularly as citrate soluble P205.

In preparing mixed fertilizers in accordance with the present invention superphosphate or triple superphosphate is treated with ammonia either in the presence of ammonium nitrate or with ammonium nitrate mixed with the superphosphate after its treatment with the ammonia and water. The ammonia is employed in amount suflicient to cause reversion of, available P205 of the superphosphate to an unavailable form except for the influence of the ammonium nitrate in repressing this tendency to cause reversion. In thus treating superphosphate, the ammonia is employed in amount corresponding to substantially more than 23 pounds NHs (at least 24 and preferably about 30 to 40 pounds NH3) for every 1000 pounds of superphosphate. In treating a triple superphosphate, for example one contain the" phosphate or triple superphosphate being treated I either as aqua ammonia, anhydrous liquid or gaseous ammonia. It is preferred to employ the ammonia either as aqua Q ammonia containing below about NHa or as liquid anhydrous ammonia. When either gaseous or liquid anhydrous ammonia are used, it is preferred to also treat the phosphate with water in amount corresponding to a ratio of water to ammonia above about 3 to 2 by weight, The ammonia and water may simultaneously be added to the superphosphate, or in series, first one and then the other. The amount of ammonium nitrate may be varied within relatively wide limits. For example, 40 pounds or more of ammonium nitrate may be employed for every 1000 pounds of superphosphate, although it is preferred to employ from to 200 pounds of ammonium nitrate for every 1000 pounds of superphosphate. The ammonium nitrate may be added as the solid mixed with the superphosphate prior to or simultaneously with the ammoniation of the superphosphate, or the superphosphate which has been ammoniated by treatment with ammonia and water may be mixed with solid ammonium nitrate. The ammonium nitrate also may be added simultaneously with the ammonia and/or the water as an aqueous solution or an anhydrous ammoniacal solution of the ammonium nitrate.

Particularly when employing relatively concentrated aqua ammonia or anhydrous liquid ammonia for the treatment ofsuperphosphates in accordance with this invention, it is advan tageous to employ the ammonium nitrate in solution in the ammoniacal liquid and to mix ammonium sulfate with the superphosphate, preferably before the addition to it of the ammoniacal solutionof ammonium nitrate. Accordingly, this invention includes the preparation of fertilizers by treating a superphosphate with an ammoniacal solution of ammonium nitrate, containing for example, less than about 60 parts of water for every 40 parts of ammonia (corresponding to solutions of ammonium nitrate in liquid anhydrous ammonia or an aqua ammonia of a strength greater than about 40% N'Ha) and mixing ammonium sulfate with the phosphate. The ammoniacal liquid is added to the phosphate in amount corresponding to the above proportions of ammonia to phosphate. The ammonium sulfate'is preferably mixed with the phosphate either prior to or simultaneously with its treatment with f the ammoniacal solution of ammonium nitrate.

The following examples are illustrative of this invention:

Example I.superphosphate and ammonium nitrate are mixed in the proportions of 1000 pounds of superphosphate to 100 pounds of ammoniumnitrate. With this mixture there is incorporated 148 pounds of aqua ammonia containmg 25% NHs. The ammonia is thus added in the proportions of 37 pounds of ammonia for every 1000 pounds of superphosphate. The resulting mixture is allowed to cure and is then ready for. shipment and use as a fertilizer. I

The foregoing procedure may be modified to first incorporate with the superphosphate the aqua ammonia and then mix the ammonium nitrate with the ammoniated superphosphate.

Example II.Superphosphate and ammonium nitrate are mixed in the proportions of 200 pounds of ammonium nitrate for every 1000 pounds of superphosphate. With this mixture there is incorporated 148 pounds of aqua ammonia containing 25% NH3 and the resulting mixture allowed to cure. I

Example III .-Ammonium nitrate is mixed with superphosphate in the proportions of about 100 pounds of ammonium nitrate to 1000 pounds of superphosphate. The resulting mixture is then treated with 220 pounds taining 25% NH3. The resulting mixture is then dried and cured to obtain a product having satisfactory physical characteristics as a fertilizer.

Example IV.About 40' parts of a solution of ammonium nitrate and water containing 70% ammonium nitrate is mixed with about 35'parts Into this solution is introduced 25 preferably as liquid ammonia.

of water. parts of ammonia,

of aqua ammonia con This solution is then mixed with superphosphate, with or without other materials, in suchquantity that there is available about 2 molecular weights of ammonia for reaction with each molecular weight of water soluble P205 in the superphosphate. The chemical reactions which take place and which result in the liberation of heat exercise a drying action on the mixture and a product is obtained which dries quickly to a friable material which is stable, easily handled, relatively non-hygroscopic, and of excellent fertilizer value.

In preparing a fertilizer according to the foregoing procedure, the aqueous ammon'iacal solution of ammonium nitrate which is added to the superphosphate contains the following ingredients in the indicated proportions by weight: 28 parts ammonium nitrate, 25 parts ammonia and 47 parts water. The liquid composition, therefore, corresponds to a solution of ammonium nitrate in an aqua ammonia containing about 85% NHa. In adding such a composition to superphosphate so that about 2 molecular weights of ammonia are available for reaction with each molecular weight of water soluble P205, about 150 pounds of the foregoing liquid composition would be added superphosphate used correspond to about parts of ammonium nitrate and 32 parts of ammonia for every 1000 parts of superphosphate.

Example VI.-41 parts of superphosphate, 20

parts manure salts, 12.5 parts sulfate of ammonia,

10 parts organics and 9 parts sand are admixed and the admixture so obtained treated with 7.5 parts of a solution of ammonium nitrate in liquid ammonia containing about 3.3 pounds ammonium nitrate perpound of ammonia (NHa). In this examplethe ammonia is employed in the proportions of 42.5 parts of ammonia to every 1000 parts of superphosphate.

Example TIM-+85 parts of superphosphate are treated with 15 parts of a solution of ammonium nitrate in liquid ammonia containing 3.3 pounds of ammonium nitrate for every one pound of ammonia (NI-I3), In this example the ammonia is employed in the proportions of 41 parts of ammonia to every 1000 parts of superphosphate.

Example VIII.About 76.5 parts of superphos- 1 phate are treated with 23.5 parts of a solution consisting of 66.7% ammonium nitrate, 13.3%

ammonia and 20% water. In thus preparing a fertilizer the ammonium nitrate, ammonia and superphosphate are employed iii-the proportions of about 205 parts of ammonium nitrate and about 40 parts of ammonia for of superphosphate. The solution containing ammonium nitrate, ammonia and water corresponds to a solutionof ammonium nitrate in an aqua ammonia containing about 40% N11}.-

Earample IX.34.8 parts of triple superphosphate, 15.8 parts of ammonium nitrate, 16 parts of muriate of potash and 21.4 parts of filler, for example sand, are admixed and the admixture so obtained treated with 12 parts of ammonia in the form of a 25.7% ammonia liquor. In this example the ammonia is employed in the proporevery 1000 parts.

tions of 89 parts of ammonia to every 1000 parts of triple superphosphate.

Eazample X.33.4 parts of triple superphosphate containing about45% P205, 3.3 parts of ammonium sulfate, 15 parts of peat, 16 parts of muriate of potash and 15.3 parts of filler, for example sand, are admixed and the admixture thus obtained is treated with 17 parts of a solution containing ammonium nitrate and ammonia.

ammonia for every 1000 parts of triple superphosphate.

The invention affords a simple and effective method of preparing fertilizer mixtures and permits the utilization of ammonia in making up mixed fertilizers from superphosphate while minimizing the loss of available P205 due to the tendency of the ammonia to convert P205 in the supertrate, urea, ammonium chloride, ammonium phosphate, and the like, which may be added to the superphosphate either prior to, simultaneously with, or after its treatment with the ammonia I and ammonium nitrate.

We claim:

1. The process for the preparation of fertilizers which comprises treating a superphosphate material with ammonium nitrate in the proportions of above about 40 pounds ammonium nitrate to @very 1000 pounds of said superphosphate and wi ammonia in amount substantially greater than that corresponding to the equation NH3= 00128 P2O5X phosphate.

2. The process for the preparation of fertilizers which comprises treating superphosphate material with ammonium nitrate in the proportions of above about 40 pounds ammonium nitrate to every 1000 pounds of said superphosphate and with ammonia in amount substantially greater than 23 pounds of ammonia for every 1000 pounds of superphosphate.

3. The process for the preparation of a fertilizer which comprises incorporating with superphosphate, ammonium nitrate, ammonia and water in the proportions of about 100 to 200 pounds of ammonium nitrate and substantially more than 23 pounds of ammonia for every 1000 pounds of superphosphate, said water and ammonia being employed in a ratio above 3 to 2.

EDWARD W. HARVEY. RUSSELL M. JONES. 

